the colours of certain Lejndoptei'a. 471 



lead them in the direction of concealment. It by no means 

 follows that the power is useless in certain species because 

 it leads to more perfect results in others. Concerning the 

 latter, no one who has once seen the larvae of A. hetularia 

 or R. crata-r/ata upon their food-plants in the field, can 

 doubt about the meaning of the changes in colour which 

 they undergo. 



The pupae of many species have now been tested, and 

 only in the case of one of them (F. urticcs) has any doubt 

 been expressed as to the efficiency of the change in pro- 

 moting concealment. The cases of Vanessa io and the 

 Picridcs (including P. na})i) are nearly as clear as those 

 of A. hetularia and B.. craiagata, and the same may be 

 said of a few S. African species tested by Mrs. M. E. 

 Barber, Mr. Eoland Trimen, and Mr. Mansel Weale, The 

 changes of Vanessa atalanta and T^ yolychloros certainly 

 lead in the same direction ; and there is not that exces- 

 sive development of the golden appearance in the lighter 

 forms which, in V. urticce, is thought by some to be a 

 conclusive argument against the protective significance 

 of the change. 



In Argynnis 2xi2yhia we have a very interesting case. 

 There can be no doubt about the change being strongly in 

 the direction of concealment, but the metallic spots (which 

 are not very large) are equally present in both dark and 

 light pupae. The ancestral relationship of the Argyiinidce 

 to the Vancssidce, as shown by Dr. Dixey in the com- 

 parison of the wing markings, suggests the possibility 

 that the metallic sf)ots are an ancestral feature of both 

 pupae which can be removed from the darker forms of 

 Vancssidce, but remain in the lighter ones, while they 

 persist in both varieties of at least one species of 

 Argynnis. In this respect it is interesting to note that 

 the position of each metallic spot can generally be de- 

 tected by its lighter colour in the dark pupae of such 

 species as V. polycldoros or V. atalanta. 



I must now consider the case of V. urticce at greater 

 length, because of the arguments brought forward by 

 Mr. Bateson in a recent paper (Trans. Ent. Soc, Lond., 

 1892, pp. 212, 213). 



This writer, in the first place, attempts to cut awa}^ 

 the foundation of an interpretation based on natural 

 selection, by arguing that there is no struggle for exist- 

 ence during the pupal stage of this species. 



